Module cover for airbag apparatus

ABSTRACT

A module cover for an airbag apparatus. The module cover includes a plate member and a leg member. The leg member extends from the back surface of the plate member. The plate member and the leg member are formed separately and joined after formation. The plate member is formed of thermoplastic elastomer.

BACKGROUND

[0001] The present invention relates to an module cover for an airbagapparatus.

[0002] An airbag apparatus installed in a high-speed movable body suchas a motor vehicle includes a folded airbag, a retainer to which theairbag is mounted, an inflator (gas generator) for deploying the airbag,and a module cover covering the airbag. The module cover includes a topplate member and a leg strip member standing upright from the backsurface of the top plate member. The leg strip member is connected tothe retainer.

[0003] When the inflator generates gas, the airbag starts deployment,the module cover is broken and pushed opened along a tear line, and theairbag is deployed in the vehicle cabin, so that an occupant isprotected.

[0004] In Japanese Unexamined Patent Application Publication No.2002-12116 (incorporated by reference herein), a module cover in which atop plate member and a leg strip member are formed separately ofsynthetic resin and are joined by vibration welding is disclosed. Whenthe top plate member and the leg strip member are integrally molded,there is a tendency that molding sink is generated on the front surfaceof the top plate member at the portion of the top plate membercontinuing from the leg strip member. However, when the top plate memberand the leg strip member are formed separately and joined together, suchmolding sink on the front surface of the top plate member is avoided,and thus a module cover which is superior in appearance is obtained.

[0005] In the module cover disclosed in the above described JapaneseUnexamined Patent Application Publication No. 2002-12116, the leg stripmember has a square shape including a plate-shaped reinforcing memberoverlapping with the back surface of the top plate member and a mountingportion extending upright from the peripheral edge of the reinforcingportion. When the square-shaped leg strip member is joined to the topplate member by vibration welding, the reinforcing member is fixed tothe area near the center of the top plate member. Therefore, rigidity ofthe top plate member is increased, and thus a force required for openingthe top plate member when the airbag is deployed increases as well. Inaddition, a high-power inflator must be employed correspondingly.

[0006] Accordingly, there remains a need for a module cover for anairbag apparatus in which the top plate member can easily be opened whenthe airbag is deployed.

SUMMARY OF THE INVENTION

[0007] According to an embodiment of the present invention, a modulecover for an airbag apparatus is provided. The module cover includes atop plate member and a leg strip member standing upright from the backsurface of the top plate member. The top plate member and the leg stripmember are formed separately from each other and are joined afterformation. The top plate member is preferably formed of thermoplasticelastomer.

[0008] Since the top plate member is preferably formed of thermoplasticelastomer, which is relatively high in flexibility, the top plate membercan be pushed open with a relatively small force when the airbag isdeployed.

[0009] Since the top plate member and the leg strip member are formedseparately, molding sink on the front surface of the top plate member isavoided. Thus, a module cover which is superior in appearance isobtained.

[0010] According to another embodiment of the present invention, the legstrip member is preferably formed of thermoplastic resin. The leg stripmember and the top plate member are joined by vibration welding so thatboth of them can be easily and stably connected.

[0011] According to another embodiment of the present invention, the legstrip member includes a base portion joined with the back surface of thetop plate member and a leg strip body standing upright from the baseportion and extending away from the back side of the top plate member.The base portion exists only on the side of the outer periphery of thetop plate member with respect to the leg strip body.

[0012] In this arrangement, since the base portion of the leg stripmember is disposed only on the outside of the top plate member withrespect to the leg strip body, rigidity of the top plate member insidethe leg strip member is not increased by the base portion. Therefore, itis not necessary to increase the output of the inflator, and thus thetop plate member can open smoothly when the airbag is deployed.

[0013] In this mode, for example, the top plate member and the leg stripmember can easily and stably be connected by forming the leg stripmember of, for example, thermoplastic resin and joining the base portionof the leg strip member with the back surface of the top plate member byvibration welding.

[0014] According to another embodiment of the present invention, themodule cover may be constructed in such a manner that a projection isformed from the back surface of the top plate member, the projection isinserted into an opening provided on the base portion, and the top platemember and the leg strip member are joined by undetachable engagementbetween the projection and the opening. In this arrangement, the topplate member and the leg strip member are stably connected. For example,the projection and the opening are brought into undetachable engagementby the extremity of the projection being enlarged by caulking, and theprojection and the opening are brought into undetachable engagement by aclip being attached on the extremity of the projection. In thisconstruction, the top plate member and the leg strip member are easilyconnected.

[0015] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the invention claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] These and other features, aspects, and advantages of the presentinvention will become apparent from the following description, appendedclaims, and the accompanying exemplary embodiments shown in thedrawings, which are described briefly below.

[0017]FIG. 1 is a vertical cross section of an airbag apparatus having amodule cover according to an embodiment of the present invention.

[0018]FIG. 2 is a bottom perspective view of the module cover shown inFIG. 1.

[0019]FIG. 3 is an exploded perspective view of the module cover shownin FIG. 2.

[0020]FIG. 4 is a cross sectional view of a module cover according to anembodiment of the present invention.

[0021]FIG. 5(a) is a cross sectional view of a module cover according toan embodiment of the present invention

[0022]FIG. 5(b) is an exploded perspective view of the module covershown in FIG. 5(a).

DETAILED DESCRIPTION

[0023] Embodiments of the present invention will be described below withreference to the accompanying drawings.

[0024] According to an embodiment of the present invention, as shown inFIG. 1, the airbag apparatus is an airbag for a front passenger seat tobe installed in an instrument panel (not shown), and includes a foldedairbag 10; a container-shaped retainer 12 to which the airbag 10 isattached via a mounting fixture 16; an inflator 14 for deploying theairbag 10; a module cover 20 for covering the airbag 10; and aconnecting fixture 32 secured to the retainer 12 by welding or the like.

[0025] The module cover 20 includes a top plate member 22 to be disposedso as to be flush with the instrument panel therearound and a leg strip(or frame) member 24 joined on the back surface of the top plate member22. The top plate member 22 is formed with a tear line 22 a formed of agroove. The leg strip member 24 includes a base portion 26 joined to theback surface of the top plate member 22 and a leg strip body (orextension member) 28 standing upright from the base portion 26 towardthe back side of the top plate member 22. The leg strip body 28 isprovided with an engaging hole 30 of a hooking member 32 a of theconnecting fixture 32.

[0026] In this embodiment, as shown in FIG. 2, the leg strip body 28 isshaped like a rectangular frame so as to enclose the entire periphery ofthe retainer 12. The base portion 26 is provided in a flange shapeextending outward from the edge of the rectangular frame-shaped legstrip body 28. In this embodiment, the base portion 26 is providedaround the entire periphery of the leg strip body 28.

[0027] According to an embodiment of the present invention, the topplate member 22 is preferably formed of TPO (thermoplastic elastomer ofOlefin group). The leg strip member 24 is preferably formed ofthermoplastic synthetic resin. The thermoplastic resin may be TPO. Asshown in FIG. 3, the top plate member 22 and the leg strip member 24 arejoined by placing the base portion 26 on the back surface of the topplate member 22 and welding by vibration welding.

[0028] The module cover 20 is engaged with the retainer 12 so as tocover the airbag 10 and then the hooking member 32 a is engaged with theengaging hole 30.

[0029] In the airbag apparatus thus constructed, when the inflator 14 isactuated and gas is injected therefrom, the airbag 10 starts deployment,and the top plate member 22 is broken along the tear line 22 a. Then, asshown by chain double-dashed line in FIG. 1, the top plate member 22 isopened and the airbag 10 is deployed in front of an occupant sitting onthe front seat.

[0030] In the module cover 20, since the top plate member 22 ispreferably formed of TPO, which is relatively high in flexibility, andis opened as shown by chain double-dashed lines, there is a relativelysmall force along with deployment of the airbag 10.

[0031] In addition, in the module cover 20, since the base portion 26 ofthe leg strip member 24 exists only on the outside of the leg strip body28, rigidity of the top plate member 22 in the area inside the leg stripbody 28 corresponds only to rigidity of the top plate member 22.Therefore, the top plate member is bent as shown by chain double-dashedlines easily by being pressed by the deploying airbag 10. Therefore,even when a low-power inflator, of which the gas generating pressure islow, is used as the inflator 14, the airbag 10 is deployed quickly.

[0032] Having preferably formed the top plate of TPO, generation ofhangnails (such phenomena that the top plate member or the flap portionare not torn exact along the tear line and part of material remainsthereon, or flies in all directions) on the top plate member when theairbag is deployed is prevented. When the module cover is formed ofpolypropylene as disclosed in the aforementioned Japanese UnexaminedPatent Application Publication No. 2002-12116, it is necessary toprocess the module cover to form a tear line after the module cover isformed. However, according to an embodiment of the present invention,when forming the module cover using TPO, formation of the module coverand formation of the tear line can be made simultaneously. Thus, themanufacturing process can be simplified.

[0033] In the aforementioned embodiment, the top plate member 22 and theleg strip member 24 are joined by vibration welding. However, accordingto another embodiment of the present invention, as with module cover 20Aas shown in FIG. 4, it is also possible to provide an opening 40 on thebase portion 26 and a projection 42 on the back surface of the top platemember 22, inserting the projection 42 into the opening 40, enlargingthe extremity of the projection 42 by caulking, thereby joining the topplate member 22 and the leg strip member 24. In order to caulk theextremity of the projection 42, ultrasonic welding or hot gas welding,for example, can be performed.

[0034] According to another embodiment of the present invention, as withmodule cover 20B shown in FIGS. 5(a) and 5(b), it is also possible toprovide a slit-shaped opening 50 on the base portion 26 and providing aplate-shaped projection 52 on the back surface of the top plate member22, inserting the projection 52 into the opening 50, and attaching aclip fixture 56 to the projection 52 by with a bolt 58 and a nut 60,thus joining the top plate member 22 and the leg strip member 24. Theprojection 52 and the clip fixture 56 are formed with holes 52 a, 56 afor inserting the bolt 58. As a matter of course, the clip fixture 56has a size that can not pass through the opening 50.

[0035] Other construction of the module covers 20A, 20B in FIGS. 4, 5are the same as the module cover 20 described above.

[0036] The embodiment described above is illustrated as an example ofthe present invention, and modes other than described above may beemployed. For example, arrangements of the tear line may be differentfrom those shown in the drawings, and the leg strip member and theretainer may be fastened with other connecting means, such as rivets.The embodiments described above relate to an airbag apparatus for afront seat. However, the present invention may be applied to an airbagapparatus for a driver's seat or for rear seats.

[0037] As described above, according to the present invention, a modulecover having no hangnail present on the top plate member, and beingopened smoothly without increasing the power of the inflator, isproposed.

[0038] The priority document, Japanese Patent Application No.2002-360852, filed Dec. 12, 2002, is hereby incorporated by reference.

[0039] Given the disclosure of the present invention, one versed in theart would appreciate that there may be other embodiments andmodifications within the scope and spirit of the invention. Accordingly,all modifications attainable by one versed in the art from the presentdisclosure within the scope and spirit of the present invention are tobe included as further embodiments of the present invention. The scopeof the present invention is to be defined as set forth in the followingclaims.

What is claimed is:
 1. A cover for an airbag module comprising: a platemember having a top surface to be exposed to a vehicle cabin; and aframe member extending from a back surface of the plate member; whereinthe plate member and the frame member are configured to be formedseparately and joined after formation; wherein the frame member includesan opening; and wherein the plate member covers the opening.
 2. A coverfor an airbag module according to claim 1, wherein the plate member isformed of thermoplastic elastomer.
 3. A cover for an airbag moduleaccording to claim 1, wherein the frame member is formed ofthermoplastic synthetic resin.
 4. A cover for an airbag module accordingto claim 1, further comprising a bond between the plate member and theframe member.
 5. A cover for an airbag module according to claim 4,wherein the bond comprises a vibration welded bond.
 6. A cover for anairbag module according to claim 1, wherein the frame member includes abase portion.
 7. A cover for an airbag module according to claim 6,wherein the frame member includes an extension member.
 8. A cover for anairbag module according to claim 6, wherein the base portion is joinedwith the back surface of the plate member.
 9. A cover for an airbagmodule according to claim 6, further comprising a bond between the baseportion and the plate member.
 10. A cover for an airbag module accordingto claim 9, wherein the bond comprises a vibration welded bond.
 11. Acover for an airbag module according to claim 7, wherein the extensionmember extends in a direction away from the back surface of the platemember.
 12. A cover for an airbag module according to claim 11, whereinthe base portion extends from the extension member in a direction awayfrom a center portion of the plate member and in a direction toward anedge portion of the plate member.
 13. A cover for an airbag moduleaccording to claim 6, wherein the plate member includes a projectionformed on the back surface; wherein the base portion includes anaperture; and wherein the aperture is configured to accept theprojection.
 14. A cover for an airbag module according to claim 13,wherein the projection is received in the aperture.
 15. A cover for anairbag module according to claim 14, wherein an engagement between theprojection and the aperture is undetachable.
 16. A cover for an airbagmodule according to claim 14, wherein an end of the projection includesa keeper member, wherein the keeper member is configured to enlarge anend of the projection so that the projection remains engaged with theaperture.
 17. A cover for an airbag module according to claim 16,wherein the keeper member comprises caulking.
 18. A cover for an airbagmodule according to claim 14, further comprising a retaining member,wherein the retaining member is attached to an end of the projection sothat the projection remains engaged with the opening.
 19. A cover for anairbag module according to claim 18, wherein the retaining membercomprises a clip.
 20. A cover for an airbag module comprising: a platemember; and a frame member extending from a back surface of the platemember; wherein the plate member and the frame member are configured tobe formed separately and joined after formation; and wherein the platemember is formed of thermoplastic elastomer.
 21. A cover for an airbagmodule for a vehicle comprising: a plate member having a top surface tobe exposed to a vehicle cabin; a frame member connected to a backsurface of the plate member; wherein the frame member is not integralwith the plate member and includes an opening for the airbag so thatwhen deploying, the airbag does not deform the frame member.
 22. Anairbag module for protecting an occupant of a vehicle comprising: anairbag; and a cover having a plate member and a frame member; whereinthe plate member has a top surface to be exposed to a vehicle cabin andwherein the frame member extends from a back surface of the platemember; wherein the plate member and the frame member are configured tobe formed separately and joined after formation; wherein the framemember includes an opening; and wherein the plate member covers theopening.